Vertical Pocket In Pregnancy – A Reliable Method For Assessing Amniotic Fluid Volume
Amniotic fluid volume may be determined using many different approaches.
The maximum vertical pocket in pregnancy technique was explicitly designed to diagnose oligohydramnios.
For this purpose, the largest vertical dimension of the amniotic sac free of cord and limbs is used.
In most hospitals, a measurement of less than 2 centimeters is considered abnormal and may indicate oligohydramnios.
The Amniotic Fluid Index is found by adding the fluid amount in each amniotic sac.
This is part of the four-quadrant analysis used to measure the amount of amniotic fluid.
The amniotic fluid index enhances the incidence of identification of oligohydramnios and the rate of labor induction without improving peripartum outcomes, suggesting that the vertical pocket measurement in the evaluation of amniotic fluid volume during fetal monitoring is a superior option.
There has to be an in-depth analysis of the diagnostic efficacy of both techniques for identifying low amniotic fluid levels.
Amniotic fluid index (AFI) usage raises the intervention rate without improving birth outcomes.
When monitoring a fetus for amniotic fluid volume, the vertical pocket seems to be the most reliable indicator of this condition.
It seems sensible to advocate for standardizing prenatal evaluation testing on a single technique.
The fluid that surrounds the fetus during pregnancy is called amniotic fluid.
Fluid transudation over the fetal skin or the maternal decidua causes early amniotic fluid composition to resemble protein-free fetal serum.
After around 11 weeks of pregnancy, the amniotic fluid is almost all fetal urine, with just a little quantity coming from the lungs.
There seems to be a balance between the input of fetal urine and the output of fetal swallowing and intramembranous water flow that determines the amount of amniotic fluid (from amniotic fluid across the amnion into the fetal-placental vasculature).
During the first two trimesters, the amniotic fluid builds up steadily.
It reaches its highest level between 33 and 34 weeks of pregnancy.
In pregnant women, a low amniotic fluid volume is referred to as oligohydramnios.
A maximal vertical pocket (MVP) of less than 2 cm or an AFI of less than 5 cm characterizes oligohydramnios.
Anhydramnios is diagnosed when there is no detectable amount of amniotic fluid in the uterine cavity.
Research has shown that oligohydramnios is associated with a higher risk of perinatal death and morbidity.
Corresponding adjusted perinatal death rates were 109.4 per 1000, 37.74 per 1000, and 1.97 per 1000 for MVP 1 cm, MVP 1-2 cm, and MVP > 2 cm and 8 cm, respectively.
Some of the causes of oligohydramnios (insufficient amniotic fluid) are as follows: Membranes that have ruptured
- Abnormalities at birth
- Growth restraint (placental insufficiency)
- Pregnancy after term:
- Medications like angiotensin-converting enzyme inhibitors and prostaglandin synthase inhibitors.
- Transfusion from twin to twin
- TRAP (twin reverse arterial perfusion sequence)
- Idiopathic fetal death
Polyhydramnios is characterized by an abnormally high amount of amniotic fluid in relation to the gestational age of the fetus.
Polyhydramnios is diagnosed when the maximal vertical pocket is 8 cm or higher, or when the AFI is 24 cm or higher.
Idiopathic polyhydramnios accounts for 50 to 60% of all polyhydramnios cases, and this type of the condition has been linked to an increased risk of fetal macrosomia and other negative pregnancy outcomes.
A higher risk of perinatal death and morbidity has been linked to polyhydramnios as well.
Overly abundant amniotic fluid, or polyhydramnios, may result from a number of different factors.
- In most instances, the cause is idiopathic.
- Esophageal atresia, intestinal blockage, and other gastrointestinal disorders Defects of the central nervous system, such as anencephaly,
- Chromosomal abnormalities
- This case of hydrops was caused by an autoimmune process, but it might have been anything.
- Disorders of the skeleton
- Transfusion between identical twins
It has been shown that measuring the depth of the ultrasound's deepest (maximal) vertical pocket in pregnancy is an accurate way to estimate the amount of amniotic fluid in the uterus.
An amniotic fluid sample is taken from a deep pocket free of the umbilical cord and other fetal components.
Generally, recognized values are:
- <2 cm is an indication of oligohydramnios
- 2-8 cm is typical, but it has to be considered in the context of the subjective volume.
- A polyhydramnios diagnosis is made at >8 cm (however, other facilities, especially in Australia, New Zealand, and the United Kingdom, have a cut-off of >10 cm).
Both the maximal vertical pocket and the maximal vertical pocket have been used to measure the amount of amniotic fluid present during a twin pregnancy.
For the amniotic compartment of each twin to be separated into four quadrants, as is necessary for the maximal vertical pocket, knowledge of the spatial connection of the gestational sacs is required.
Given the technical challenges of doing so, particularly in the third trimester when fetal crowding is prevalent, it is advised that a maximal vertical pocket be used to evaluate the amount of amniotic fluid separating the two fetuses.
Between 17 and 37 weeks of pregnancy, there does not seem to be much change in the maximal vertical pocket size inside each twin's amniotic sac, with the 2.5th and 97.5th percentiles sitting at 2.3 and 7.6 cm, respectively.
The evidence supports the adoption of cut-offs of 2 cm and 8 cm to define oligohydramnios and polyhydramnios, respectively.
The quantity of amniotic fluid may be qualitatively assessed by ultrasound.
When evaluating the amniotic fluid through ultrasound, one approach involves determining the depth of the biggest visible pocket of fluid around the fetus.
In singleton pregnancies, a maximum vertical pocket depth of between 2 and 8 centimeters is typical.
In twin pregnancies, the average depth of the largest pocket is estimated to be between 2.2 and 7.5 centimeters.
|Visible pocket depth||Description|
|< 1 cm||Severe oligohydramnios|
|1 to 2 cm||Mild oligohydramnios|
|Between 2 to 8 cm||Normal|
|8 to 12 cm||Polyhydramnios|
|From 12 to less than 16 cm||Moderate polyhydramnios|
|From 16 cm and more||Severe polyhydramnios|
Using the conventional evaluation approach, a normal amniotic fluid index ranges from 5 cm to 25 cm.
Oligohydramnios is defined as less than 5 cm, whereas polyhydramnios is defined as more than 25 cm.
Most institutions consider 2 cm to be the standard minimum; less than 2 cm generally implies oligohydramnios.
The four-quadrant analysis is an alternate way of assessing AFV by calculating the Amniotic Fluid Index (AFI) by totalling the separate pockets of amniotic fluid.
In singleton gestations, the usual range for the deepest vertical pocket (or greatest vertical pocket) is 2 cm to 8 cm.
In twin gestation, the usual range for the single deepest pocket seems to be 2.2 cm to 7.5 cm.
The greatest visible pocket's depth.
Normally, the Amniotic Fluid Index (AFI) ranges from 7 to 25 cm.
Furthermore, each individual fluid pocket should be 2 to 8 cm in size.
Variations beyond this range are defined as oligohydramnios (too little amniotic fluid) or polyhydramnios (too much amniotic fluid).
The amount of amniotic fluid in a pregnant woman's vertical pocket is a qualitative measurement that may not be a good indicator of the actual amount of amniotic fluid.
The amniotic fluid index provides a standardized method for determining whether or not there is an adequate amount of amniotic fluid during pregnancy.
The amniotic fluid index may help patients who are pregnant with a single baby and have been pregnant for at least 24 weeks.
These methods can help us learn more about any problems with how a fetus grows and develops.